b. Record test conditions. 



(1) Displacement. 



(2) Drafts fore and aft. 



(3) Loading or ballasting plan. 



(4) Minimum depth of water. 



(5) Sea state estimate. 



c. Calibrate recording equipment. 



(1) System calibration - This should be done ashore before 

 every test. A positive -displacement mechanical calibrator should be 

 used to obtain overall system calibration factors. 



(2) Electrical calibration - At approximately 30-minute 

 intervals during the test, an electrical calibration signal of known 

 strength should be recorded to permit compensation for any variation 

 in signal gain (the Sample Test Report shows an acceptable method of 

 accomplishing this calibration). 



d. Take data during the following conditions: 



(1) In free route, at 5 rpm increments from 1/2 speed to 

 maximum speed. 



(2) Hard turn to port, at maximum speed. 



(3) Hard turn to starboard, at maximum speed. 



(4) Crash -back (from full power ahead to full power astern), 



(5) Anchor drop-and-snub test. 



e. Procedures for taking data. 



(1) For steady speed, straight course runs, permit ship 

 to steady on speed. Take sufficient length of record to permit collec- 

 tion of maximum and minimum values (about one mintite). 



(2) For maneuvers, start the recorder as the throttle or 

 wheel is moved. Allow to run until maximum vibration has passed. 

 This normally occurs when ship is dead in the water during crash -back 

 maneuver, or when the ship is fully in a turn. 



(3) For the anchor drop-and-snub test, the anchor must 

 fall freely for a distance of no more than 15 fathoms but at least equal 



26 



